1. Field of the Invention
This invention relates to web-fed rotary printing presses in general and, in particular, to a mechanism incorporated with such a press for infeeding a web of paper into the machine from successive web rolls as the web is spliced from one such roll to the next.
2. Description of the Prior Art
A familiar type of web infeed for a rotary printing press has two pairs of web roll carrier arms extending in opposite directions from a rotary arm carrier beam. Each pair of carrier arms rotatably carry a roll of paper web therebetween by engaging the opposite ends of the tubular core of the web roll. Held in a prescribed angular position about the axis of the carrier beam, the web roll on one pair of carrier arms first pays out its web to feed the press. When this web roll is nearly used up, the carrier beam is turned 90 degrees for splicing the web to the next web roll on the second pair of carrier arms. The carrier beam is turned another 90 degrees upon completion of web splicing, thereby bringing the second web roll to the payout position.
A variety of suggestions have been made for rotatably supporting a web roll between each pair of carrier arms. Japanese Patent No. 3,041,619 and Japanese Unexamined Patent Publication No. 2000-103553 are hereby cited as bearing particular pertinence to the instant invention. The former teaches use of hollow spindles rotatably mounted one to each carrier arm in axial alignment with each other so as to be loosely received in the opposite ends of the hollow core of a web roll. The hollow spindles on each pair of carrier arms are of like construction, each having a plurality of web roll core detents which are mounted at constant circumferential spacings thereon. All these detents are capable of fluid pressure actuation for displacement radially outwardly of the spindle into and out of frictional contact with the inside surface of the web roll core. After the web has been used up and spliced to the next roll, the web roll core is removed from between the pair of carrier arms by retracting the detents into the spindles.
An objection to this Japanese patent is an unnecessarily great dimension of the web infeed axially of the carrier beam, or transversely of the web being into the press. This inconvenience arises in part from the fact that both cylinders on each pair of carrier arms are equipped for fluid pressure actuation of the detents radially of each spindle. Additionally, the dimension in question must be made even longer because both spindles on each pair of carrier arms must travel axially into and out of the web roll core.
According to Japanese Unexamined Patent Publication No. 2000-103553, supra, each pair of carrier arms have different spindle means mounted respectively thereto. When a spindle on one carrier arm is pushed into one end of a web roll core, the other end of this core pushes in turn a tapering, spring-loaded end cap on one end of a spindle on the other carrier arm. By reaction, then, the tapering end cap is sprung back against the web roll core thereby forcing the same into axial alignment with the spindle. Detents on this spindle are also pushed by the web roll core and, by being done so, displaced radially outwardly into frictional engagement with the inside surface of the core.
This second reference additionally differs from the first in having means for forced removal of the core after consumption of all the web thereon. Such means include a set of fluid-actuated pushpins built into the spindle on each carrier arm. The pushpins on actuation cause retraction of the detents radially inwardly of the spindle out of engagement with the web roll core.
Although it possesses some advantages over the first cited reference, this second one has some shortcomings that are in urgent need of improvement. The detents on each spindle must move into frictional engagement with the inside surface of the web roll core as the spindle is forcibly inserted therein with the detents in abutment against one end of the core. This requires exertion of strong axial forces on the web roll core from its opposite ends, with the result that the spindles on each pair of carrier arms receive from the core just as strong reactive forces axially thereof. So stressed, the spindles offer correspondingly greater resistance to the rotation of the web roll and impart higher tension to the web being pulled into the press from the web roll. The web tension builds up, moreover, in inverse proportion to the diameter of the web roll. What is worse, the web must be spliced to the next roll when the web roll diameter is reduced nearly to a minimum. In the worst case, therefore, the web was broken by the forces applied thereto during splicing.
Another problem is, again, the inconveniently long dimension of this web infeed transversely of the web. One reason for this is that the fluid actuators for core removal are built into the spindles. Another reason is that the pair of spindles must both be driven into and out of the opposite ends of the web roll core.
An object of the present invention is to make the web infeed of the type under consideration more compact in construction than heretofore known in the art.
Another object of the invention is to cause the web of paper to be fed under proper tension in the face of a decreasing diameter of the web roll and hence to assure web splicing without the risk of web breakage.
Briefly, the present invention may be summarized as a web infeed for a rotary printing press, wherein a web of paper being fed into the press from a first roll of such web is spliced to a second web roll when the first web roll is used up. The web infeed comprises a carrier beam mounted to frame means for rotation about a longitudinal axis, and at least two pairs of carrier arms mounted to the carrier beam each for rotatably supporting a web roll therebetween. One of each pair of carrier arms has first spindle means and core removal means mounted thereto. The first spindle means comprises a first spindle which is rotatable relative to said one carrier arm about an axis parallel to the axis of rotation of the carrier beam and which is to be inserted in the hollow core of a web roll from one end thereof in centering engagement therewith, a plurality of detents movably mounted to the first spindle at circumferential spacings thereon and constrained to displacement radially of the first spindle, and fluid pressure actuation means built into the first spindle for moving the detents radially thereof into and out of frictional engagement with the inside surface of the web roll core when the first spindle is inserted therein. For forcibly removing the web roll core from the first spindle means following the consumption of the web that has been rolled thereon, the core removal means comprises fluid-actuated plunger means movable relative to said one carrier arm in a direction parallel to the axis of the first spindle of the first spindle means into abutment against the web roll core for pushing the same out of engagement with the first spindle means.
The other of each pair of carrier arms, on the other hand, has second spindle means mounted thereto in axial alignment with the first spindle means on said one of the same pair of carrier arms. The second spindle means comprises a second spindle rotatably mounted to said other carrier arm, and an end cap mounted to one end of the second spindle in axial alignment therewith for centering abutment against another end of the web roll core. The end cap is coupled to the second spindle so as to be free to travel a prescribed distance into and out of abutment against the second spindle and normally held a prescribed distance away therefrom under the bias of resilient means.
The web infeed according to the invention further comprises drive means for moving the second spindle means on said other of each pair of carrier arms the prescribed distance toward and away from the first spindle means on said one of the same pair of carrier arms. In one embodiment of the invention the drive means acts between the carrier beam and said other carrier arm for moving the latter with the second spindle means thereon toward and away from said one carrier arm. In another embodiment the drive means acts between said other carrier arm and the second spindle means for moving only the latter toward and away from the first spindle means on said one carrier arm.
Thus, where a web roll is mounted in position between either pair of carrier arms, the second spindle comes into abutment against the end cap in opposition to the force of the resilient means when moved by the drive means toward the first spindle. The second spindle is to be so held against the end cap until the web roll diameter dwindles to a prescribed limit toward the end of usage of all the web on that roll. As long as the second spindle is held fast against the end cap, the forces exerted axially on the web roll from both first and second spindle means are determined by the drive means.
After the web roll diameter drops past the prescribed limit, the second spindle may be permitted to travel away from the end cap under the force of the resilient means. Thereupon the axial forces on the web roll are determined by the resilient means, it being understood that the forces due to the resilient means are less than those imposed by the drive means. Thus, toward the end of web consumption, when an increasingly more unwinding force is needed in the tangential direction of the web roll, the axial forces thereon are reduced to lessen the tension on the web and hence virtually to eliminate the risk of web breakage during the ensuing course of web splicing.
The invention also teaches constant monitoring of the web roll diameter. The drive means is controlled automatically to permit the second spindle to be sprung out of abutment against the end cap upon reduction of the web roll diameter to the predetermined limit.
As a further advantage accruing from the above improved construction of the second spindle means, it is only the first spindle means that must be inserted to a certain depth into the web roll core. The dimension of this web infeed axially of the spindle means is therefore appreciably less than that according to the prior art. Additionally, no excessive forces are exerted axially on the web roll throughout the complete processes of its mounting, unwinding, and core removal, keeping the core from deformation or impairment.
It will also be appreciated that both the mounting of the web rolls between the pairs of carrier arms and the removal of the cores therefrom are mostly done from the side of the first spindle means only. The web infeed is therefore easy to inspect and maintain.
The above and other objects, features and advantages of this invention and the manner of realizing them will become more apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference had to the attached drawings showing the preferred embodiments of the invention.